1. Field of the Invention
The present invention relates to information management devices, information management systems including such information management devices and client devices, information management methods, and programs that allow computers to perform such information management methods.
2. Description of the Related Art
In recent years, networks such as the Internet and local area networks (LAN) have become widely used, and client devices can request for resources and services to application servers or devices through these types of networks. The application servers or devices receive requests from the client devices and perform various kinds of processes.
Since these application servers or devices have a limited processing ability in the CPU and a limited memory capacity, the processable amount in a single operation is physically limited. For example, in a network printing system, if a large number of print jobs are sent from a plurality of client devices to an application server or a printer so as to exceed the processing capacity of the application server or the printer, the processing may take more time than expected or may result in an error. Moreover, in some cases, this could lead to a shutdown of the application server or the printer.
In recent years, a system has been discussed in which the application server or the printer accepts print requests that do not include, for example, the rendering data of print jobs before accepting the actual print jobs, i.e. print requests, from the client devices so as to limit the storing amount of data. Such a system is discussed in, for example, Japanese Patent Laid-Open No. 10-240469. In this system, when a print request reaches its turn in the printing order of the printer, the corresponding client device sends the print job to the printer. According to this system, the application server or device can constantly perform a proper operation within its processing ability range.
However, according to the system discussed in Japanese Patent Laid-Open No. 10-240469, the system requires a server since the print-job information of the print requests is managed by a server. This is problematic for small offices since such a system leads to high costs. For this reason, there have been demands in recent years for a printer equipped with an order arrangement function for print jobs. However, providing a high-capacity memory unit (HDD) in a printer leads to an increase in the overall cost of the printer.
In order to solve this problem, a system in which a network interface (information management device) installed in the printer is provided with a RAM of about 256 megabytes is discussed. Using this memory, the printer accepts print requests that do not include the rendering data of print jobs, whereby the management of the printing order can be performed at a lower cost. However, even if only the print requests not including the rendering data of print jobs are to be managed, the amount of information to be managed, such as printing attributes, is increasing in recent years. For this reason, in the management space in the memory of the network interface, the print requests must be limited to about 256 megabytes, meaning that print requests exceeding this limit are subject to be refused.
In this system, a first client device whose print request is refused will normally try to send the print request again. However, depending on the timing at which the information management device defined by the network interface has availability for accepting print requests, there may be a case where a print request sent from a second client device after the first client device is accepted prior to the print request from the first client device. In other words, the print requests are not properly processed in the order of the print requests sent.
Furthermore, a conventional technology is also known in which the order of requests from client devices is managed by a scheduler, and the number of request is managed so as not to exceed the processing capacity of an application server or device. For example, according to Japanese Patent Laid-Open No. 2002-222123, a scheduler (i.e. a reception server) that manages the connection and the connection number of an application server is provided. Specifically, when a client device requests for a connection to the application server, the client device first sends a connection request to the scheduler. In response to a first connection request received from the client device, the scheduler issues a numbered ticket provided with a reference number. Then, the scheduler registers the connecting order of priority to the application server on a schedule table based on the reference number on the numbered ticket. Subsequently, in response to a second connection request from the client device, the scheduler allows the client device to be connected to the application server if the scheduler determines that the application server is connectable based on the connecting order of priority. Accordingly, the connection number to the application server and the order of connection requests from the client devices can be controlled.
However, in recent years, server-less systems and systems having a server function embedded in a device are becoming more common for the purpose of cutting down on the TCO (Total Cost of Ownership). For this reason, it is becoming more difficult to obtain the sufficient processing ability and reliability that are required in a server.
According to a scheduler discussed in Japanese Patent Laid-Open No. 10-240469 mentioned above, the scheduler requires a schedule table for managing the requests received from the client devices. However, an embedded server (information management device), such as the network interface, installed in the printer has a significantly limited memory capacity due to the cut-down on manufacturing costs, and for this reason, it is presumably difficult to prepare a schedule table having a dimension sufficient for the number of requests from the client devices. For example, if a large number of requests are sent from a plurality of client devices to an extent that the requests exceed the permissible limit of the schedule table, the scheduler cannot properly process the requests, and moreover, cannot follow the exact order of the requests sent. Furthermore, if the requests exceed the permissible limit of the schedule table, the scheduler could be forced to shut down.
Furthermore, according to such an embedded server incorporated in a device, the embedded server is normally turned off automatically when the power of the device is cut off. This means that the embedded server is in an environment in which it can be turned off more easily than a server that is disposed independent of a conventional printer. Since an embedded server usually does not have a secondary memory unit (a nonvolatile storage medium), when the embedded server is turned off, the schedule table is reset after every activation process. This is problematic in that during a restoring process from the power-off state, the order of requests received prior to the power-off state is lost.